Systemic immunoglobulin light chain amyloidosis

From pathogenesis to personalized treatments of neuropathies in hematological malignancies

The peripheral nervous system may be involved at any stage in the course of several hematological diseases, the most common being monoclonal gammopathies (of undetermined significance or malignant) or lymphomas. The underlying pathogenic mechanisms are different and therapies aim at targeting the dangerous either B-cell or plasma cell clones. Recently, high-throughput technologies, and next-generation sequencing have increased our knowledge of hematological diseases pathogenesis by the identification of somatic mutation affecting pivotal signaling pathways. Accordingly, new target therapies are used that may also be borrowed for treatment of neuropathies in hematological diseases.

High rate of profound clonal and renal responses with daratumumab treatment in heavily pre-treated patients with light chain (AL) amyloidosis and high bone marrow plasma cell infiltrate

Daratumumab demonstrated activity in the treatment of AL amyloidosis in two recently concluded phase II clinical trials in relapsed and refractory patients. Its role in upfront therapy is under evaluation in a phase III study. In this report we evaluated the safety and efficacy of 28-day cycles of daratumumab (single agent or combined with bortezomib or lenalidomide) in 72 previously treated patients with multiple myeloma and AL amyloidosis. Fifty (69%) were refractory to the last line of therapy. After eight infusions of daratumumab, 59 patients (82%) achieved a hematologic response, with 12 (16%) complete responses (CRs) and 30 (42%) very good partial responses (VGPRs). After 16 infusions, the quality of response improved with 22 patients (30%) achieving CR and 21 (29%) attaining VGPR. Cardiac response was observed in 11 of 37 evaluable patients (29%) and renal response in 23 of 38 patients (60%). Daratumumab is highly effective in heavily pretreated patients with relapsed/refractory AL amyloidosis and high bone marrow plasma cell burden. Renal responses, which are usually rare in this setting, were frequently observed.

Challenges in the management of patients with systemic light chain (AL) amyloidosis during the COVID-19 pandemic

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-associated coronavirus disease 2019 (COVID-19) is primarily manifested as a respiratory tract infection, but may affect and cause complications in multiple organ systems (cardiovascular, gastrointestinal, kidneys, haematopoietic and immune systems), while no proven specific therapy exists. The challenges associated with COVID-19 are even greater for patients with light chain (AL) amyloidosis, a rare multisystemic disease affecting the heart, kidneys, liver, gastrointestinal and nervous system. Patients with AL amyloidosis may need to receive chemotherapy, which probably increases infection risk. Management of COVID-19 may be particularly challenging in patients with AL amyloidosis, who often present with cardiac dysfunction, nephrotic syndrome, neuropathy, low blood pressure and gastrointestinal symptoms. In addition, patients with AL amyloidosis may be more susceptible to toxicities of drugs used to manage COVID-19. Access to health care may be difficult or limited, diagnosis of AL amyloidosis may be delayed with detrimental consequences and treatment administration may need modification. Both patients and treating physicians need to adapt in a new reality.

AL amyloidosis: advances in diagnosis and management

Light chain (AL) amyloidosis is a disease in which malignant plasma cell clones affect multiple organs including the heart and kidney. The mechanism for organ function deterioration in AL amyloidosis differs from multiple myeloma. Thus, not all agents used to treat multiple myeloma shows similar efficacy in AL amyloidosis. In AL amyloidosis, both hematologic and organ responses after treatment are important to improve the clinical outcome. Especially, improving heart function is one of the key aspects in the treatment of AL amyloidosis. With recent advances in the understanding of the pathophysiologic mechanism of AL amyloidosis, novel treatment methods are under active trial. In this article, I have reviewed the advances in pathophysiology, diagnosis, risk stratification, and treatment of AL amyloidosis.

Bortezomib, Melphalan, and Dexamethasone for Light-Chain Amyloidosis

PURPOSE

Oral melphalan and dexamethasone (MDex) were considered a standard of care in light-chain (AL) amyloidosis. In the past decade, bortezomib has been increasingly used in combination with alkylating agents and dexamethasone. We prospectively compared the efficacy and safety of MDex and MDex with the addition of bortezomib (BMDex).

METHODS

This was a phase III, multicenter, randomized, open-label trial. Patients were stratified according to cardiac stage. Patients with advanced cardiac stage (stage IIIb) amyloidosis were not eligible. The primary end point was hematologic response rate at 3 months. This trial is registered with ClinicalTrials.gov identifier NCT01277016.

RESULTS

A total of 109 patients, 53 in the BMDex and 56 in the MDex group, received ≥ 1 dose of therapy (from January 2011 to February 2016). Hematologic response rate at 3 months was higher in the BMDex arm (79% v 52%; P = .002). Higher rates of very good partial or complete response rates (64% v 39%; hazard ratio [HR], 2.47; 95% CI, 1.30 to 4.71) and improved overall survival, with a 2-fold decrease in mortality rate (HR, 0.50; 95% CI, 0.27 to 0.90), were observed in the BMDex arm. Grade 3 and 4 adverse events (the most common being cytopenia, peripheral neuropathy, and heart failure) were more common in the BMDex arm, occurring in 20% versus 10% of cycles performed.

CONCLUSION

BMDex improved hematologic response rate and overall survival. To our knowledge, this is the first time a controlled study has demonstrated a survival advantage in AL amyloidosis. BMDex should be considered a new standard of care for AL amyloidosis.

Novel challenges in the management of immunoglobulin light chain amyloidosis: from the bench to the bedside

INTRODUCTION

Immunoglobulin light chain (AL) amyloidosis is one of the most frequent systemic amyloidosis in Western countries. It is caused by a B-cell clone producing a misfolded light chain (LC) that deposits in organs.

AREAS COVERED

The review examines recent findings on pathophysiology and clinical management of AL amyloidosis. It contains an update on the recent hot topics as novel therapeutic approaches, definition of relapse, and hematologic response assessment. To review literature on AL amyloidosis, a bibliographic search was performed using PubMed.

EXPERT OPINION

Due to the proteotoxicity of amyloidogenic LCs, the therapeutic goal is a rapid and profound decrease in their concentration. The standard treatment is a risk-adapted chemotherapy targeting the B-cell clone. Novel, promising drugs, as daratumumab, are currently under evaluation in newly-diagnosed and relapsed/refractory patients. New sensitive techniques, as mass spectrometry approach and bone marrow minimal residual disease assessment, are available to evaluate depth of response. After first-line therapy, increase in LC concentration may precede worsening of organ dysfunction and should be considered carefully. Further clarification of molecular mechanisms of the disease are shedding light on new possible therapeutic targets. Innovative treatment strategies and novel technologies will improve our ability to treat AL amyloidosis, preventing organ deterioration.

Time to Redefine Risk-Stratification and Response Criteria in Immunoglobulin Light Chain Amyloidosis?

Immunoglobulin light chain (AL) amyloidosis results from clonal plasma cell (PC)-derived immunoglobulin light chain-mediated end-organ dysfunction, the extent and severity of which predicts survival. Anti-PC therapies reduce clonal light chain burden, which usually results in improvement of organ function, and consequently overall survival. Response assessment is critical to gauge therapeutic efficacy, to report clinical trial outcomes, and to switch therapy in those without response. Response in AL amyloidosis is 2-fold: hematologic response and organ response (OR). Depth of hematologic response is graded on the basis of serum free light chain (sFLC) parameters, but assessment of OR is binary. The role of normal sFLC ratio or complete remission as a treatment end point has been challenged, thus highlighting the need to quantify involved FLC and residual PC beyond the normal sFLC ratio to possibly account for the ongoing organ damage seen in some patients with complete remission. Mass spectrometry and urinary exosome represent ultrasensitive strategies to estimate involved FLC below the detection threshold of current sFLC assays. The role of new sFLC parameters and minimal residual disease as potential prognostic parameters has been recognized. Brain natriuretic peptide (BNP) and 24-hour proteinuria:estimated glomerular filtration rate ratio were identified to overcome certain limitations of N-terminal-Pro-BNP, 24-hour proteinuria, and estimated glomerular filtration rate for cardiac and renal response assessment, respectively. Use of monoclonal antibodies targeting PC and amyloid deposits has expanded the therapeutic armamentarium of AL amyloidosis, and given their excellent efficacy, early ORs are reported. This review provides insights into recent advances in the risk-stratification and response assessment of patients with AL amyloidosis in light of the changing therapeutic paradigms. Incorporation of these advancements into formal consensus guidelines would require further validation.

A case report of gastric amyloidosis due to multiple myeloma mimicking gastric cancer

Background

Gastrointestinal (GI) amyloidosis is a rare complication of multiple myeloma (MM). Due to its nonspecific clinical presentation and endoscopic appearance, an early and accurate diagnosis of GI amyloidosis is difficult. Here, we report a case of GI amyloidosis due to MM, which initially presented as GI manifestations mimicking gastric cancer.

Case presentation

A 68-year-old woman presented to the hospital with a 6-month history of anemia, coupled with a recent onset of poor appetite and vomiting for 10 days. Esophagogastroduodenoscopy revealed a gastric antrum mucosal bulge that appeared on visual inspection to be a tumor. As a result, gastric cancer was suspected. However, gastric antrum biopsies demonstrated mild chronic superficial gastritis and esophageal biopsies demonstrated moderate-to-severe atypical hyperplasia of the squamous epithelium. A second endoscopy revealed massive gastric retention and a gastric antrum mucosal bulge with surface erosion. Ultimately, an upper GI tract biopsy demonstrating positive Congo red staining and a bone marrow biopsy indicating plasmacytosis confirmed the diagnosis of gastric amyloidosis due to MM.

Conclusion

This case demonstrates that MM should be considered in patients with nonspecific GI manifestations, and in such cases, a biopsy with Congo red staining should be considered to confirm GI amyloidosis. Early detection of GI amyloidosis will ultimately improve outcomes for these rare patients.

Treating Protein Misfolding Diseases: Therapeutic Successes Against Systemic Amyloidoses

Misfolding and extracellular deposition of proteins is the hallmark of a heterogeneous group of conditions collectively termed protein misfolding and deposition diseases or amyloidoses. These include both localized (e.g. Alzheimer’s disease, prion diseases, type 2 diabetes mellitus) and systemic amyloidoses. Historically regarded as a group of maladies with limited, even inexistent, therapeutic options, some forms of systemic amyloidoses have recently witnessed a series of unparalleled therapeutic successes, positively impacting on their natural history and sometimes even on their incidence. In this review article we will revisit the most relevant of these accomplishments. Collectively, current evidence converges towards a crucial role of an early and conspicuous reduction or stabilization of the amyloid-forming protein in its native conformation. Such an approach can reduce disease incidence in at risk individuals, limit organ function deterioration, promote organ function recovery, improve quality of life and extend survival in diseased subjects. Therapeutic success achieved in these forms of systemic amyloidoses may guide the research on other protein misfolding and deposition diseases for which effective etiologic therapeutic options are still absent.

Systemic Amyloidosis Recognition, Prognosis, and Therapy: A Systematic Review

IMPORTANCE

Many patients with systemic amyloidosis are underdiagnosed. Overall, 25% of patients with immunoglobulin light chain (AL) amyloidosis die within 6 months of diagnosis and 25% of patients with amyloid transthyretin (ATTR) amyloidosis die within 24 months of diagnosis. Effective therapy exists but is ineffective if end-organ damage is severe.

OBJECTIVE

To provide evidence-based recommendations that could allow clinicians to diagnose this rare set of diseases earlier and enable accurate staging and counseling about prognosis.

EVIDENCE REVIEW

A comprehensive literature search was conducted by a reference librarian with publication dates from January 1, 2000, to December 31, 2019. Key search terms included amyloid, amyloidosis, nephrotic syndrome, heart failure preserved ejection fraction, and peripheral neuropathy. Exclusion criteria included case reports, non-English-language text, and case series of fewer than 10 patients. The authors independently selected and appraised relevant literature.

FINDINGS

There was a total of 1769 studies in the final data set. Eighty-one articles were included in this review, of which 12 were randomized clinical trials of therapy that included 3074 patients, 9 were case series, and 3 were cohort studies. The incidence of AL amyloidosis is approximately 12 cases per million persons per year and there is an estimated prevalence of 30 000 to 45 000 cases in the US and European Union. The incidence of variant ATTR amyloidosis is estimated to be 0.3 cases per year per million persons with a prevalence estimate of 5.2 cases per million persons. Wild-type ATTR is estimated to have a prevalence of 155 to 191 cases per million persons. Amyloidosis should be considered in the differential diagnosis of adult nondiabetic nephrotic syndrome; heart failure with preserved ejection fraction, particularly if restrictive features are present; unexplained hepatomegaly without imaging abnormalities; peripheral neuropathy with distal sensory symptoms, such as numbness, paresthesia, and dysesthesias (although the autonomic manifestations occasionally may be the presenting feature); and monoclonal gammopathy of undetermined significance with atypical clinical features. Staging can be performed using blood testing only. Therapeutic decision-making for AL amyloidosis involves choosing between high-dose chemotherapy and stem cell transplant or bortezomib-based chemotherapy. There are 3 therapies approved by the US Food and Drug Administration for managing ATTR amyloidosis, depending on clinical phenotype.

CONCLUSIONS AND RELEVANCE

All forms of amyloidosis are underdiagnosed. All forms now have approved therapies that have been demonstrated to improve either survival or disability and quality of life. The diagnosis should be considered in patients that have a multisystem disorder involving the heart, kidney, liver, or nervous system.

Amyloidosis in Heart Failure

PURPOSE

Amyloidosis represents an increasingly recognized but still frequently missed cause of heart failure. In the light of many effective therapies for light chain (AL) amyloidosis and promising new treatment options for transthyretin (ATTR) amyloidosis, awareness among caregivers needs to be raised to screen for amyloidosis as an important and potentially treatable differential diagnosis. This review outlines the diversity of cardiac amyloidosis, its relation to heart failure, the diagnostic algorithm, and therapeutic considerations that should be applied depending on the underlying type of amyloidosis.

RECENT FINDINGS

Non-biopsy diagnosis is feasible in ATTR amyloidosis in the absence of a monoclonal component resulting in higher detection rates of cardiac ATTR amyloidosis. Biomarker-guided staging systems have been updated to facilitate risk stratification according to currently available biomarkers independent of regional differences, but have not yet prospectively been tested. Novel therapies for hereditary and wild-type ATTR amyloidosis are increasingly available. The complex treatment options for AL amyloidosis are improving continuously, resulting in better survival and quality of life. Mortality in advanced cardiac amyloidosis remains high, underlining the importance of early diagnosis and treatment initiation. Cardiac amyloidosis is characterized by etiologic and clinical heterogeneity resulting in a frequently delayed diagnosis and an inappropriately high mortality risk. New treatment options for this hitherto partially untreatable condition have become and will become available, but raise challenges regarding their implementation. Referral to specialized centers providing access to extensive and targeted diagnostic investigations and treatment initiation may help to face these challenges.

Amyloidosis Masquerading as Alcohol-Related Cirrhosis

Amyloidosis can affect multiple organs, and involvement of the heart is the most common cause of death. Signs and symptoms vary depending upon the organ system affected by amyloid. Liver involvement is often seen, but symptoms are usually mild and nonspecific in isolated hepatic amyloidosis. None of the laboratory markers and imaging is characteristic of this condition; therefore, diagnosis is often delayed. Tissue biopsy is required for definitive diagnosis. Herein, we report a case where the patient's symptoms had been attributed to alcohol-related cirrhosis; however, further workup ultimately led to a diagnosis of systemic amyloidosis with multi-organ involvement.

Monoclonal Gammopathies of Renal Significance: Renal Biopsy and Beyond

Monoclonal Gammopathies of Renal Significance (MGRS) are a rather heterogeneous group of renal disorders caused by a circulating monoclonal (MC) immunoglobulin (Ig) component, often in the absence of multiple myeloma (MM) or another clinically relevant lymphoproliferative disorder. Nevertheless, substantial kidney damage could occur, despite the "benign" features of the bone-marrow biopsy. One example is renal amyloidosis, often linked to a small clone of plasma cells, without the invasive features of MM. However, patients with amyloidosis may present with a nephrotic syndrome and renal failure, eventually leading to end-stage kidney disease. At the same time, other organs, such as the heart and the liver, may be severely damaged by Ig light chains or amyloid deposits, occasionally resulting in fatal arrhythmias and/or organ failure. Acute kidney injury (AKI) may as well result from massive excretion of MC proteins, with deposition disease in glomeruli or renal tubules, not rarely obstructed by luminal aggregates, or "casts". Proliferative glomerulonephritis with monoclonal Ig deposits is another, less frequent clinical presentation of an MGRS. The present review deals with the implications of MGRS for renal function and prognosis, and the potential of tools, such as the renal biopsy, for assessing clinical risk and guiding therapy of the underlying condition.

Prognosis and Staging of AL Amyloidosis

The treatment options for systemic light chain amyloidosis (AL) are currently widening in an unprecedented way, brought about by an expanding arsenal of anti-myeloma therapy as well as by novel approaches to target toxic light chains and, most recently, deposited amyloid directly. In this context, accurate estimates of prognosis in AL, which allow for reliable patient advice and for example comparison of different therapies, are particularly important to clinicians. Some biomarkers and especially the genetic background of the underlying clonal disease as evaluated by interphase fluorescence in situ hybridization even have predictive value, enabling an appropriate treatment selection. Derived from the most frequently involved organs in AL, heart and kidney, this review focuses on overall survival and renal survival. A comprehensive overview and summary of reported prognostic factors and biomarkers in AL is given and the most important and validated factors are highlighted. Finally, established staging systems in AL as well as validated and perspective response criteria are presented.

Structural basis for the stabilization of amyloidogenic immunoglobulin light chains by hydantoins

Misfolding and aggregation of immunoglobulin light chains (LCs) leads to the degeneration of post-mitotic tissue in the disease immunoglobulin LC amyloidosis (AL). We previously reported the discovery of small molecule kinetic stabilizers of the native dimeric structure of full-length LCs, which slow or stop the LC aggregation cascade at the outset. A predominant structural category of kinetic stabilizers emerging from the high-throughput screen are coumarins substituted at the 7-position, which bind at the interface between the two variable domains of the light chain dimer. Here, we report the binding mode of another, more polar, LC kinetic stabilizer chemotype, 3,5-substituted hydantoins. Computational docking, solution nuclear magnetic resonance experiments, and x-ray crystallography show that the aromatic substructure emerging from the hydantoin 3-position occupies the same LC binding site as the coumarin ring. Notably, the hydantoin ring extends beyond the binding site mapped out by the coumarin hits. The hydantoin ring makes hydrogen bonds with both LC monomers simultaneously. The alkyl substructure at the hydantoin 5-position partially occupies a novel binding pocket proximal to the pocket occupied by the coumarin substructure. Overall, the hydantoin structural data suggest that a larger area of the LC variable-domain-variable-domain dimer interface is amenable to small molecule binding than previously demonstrated, which should facilitate development of more potent full-length LC kinetic stabilizers.

Solid Organ Transplantation in Amyloidosis

Amyloidosis comprises a diverse group of diseases characterized by misfolding of precursor proteins which eventually form amyloid aggregates and preceding intermediaries, which are deposited in target tissues causing progressive organ damage. In all forms of amyloidosis, vital organs may fail; depending on the specific amyloidosis type, this may occur rapidly or progress slowly. Beyond therapies to reduce the precursor protein (chemotherapy for light chain [AL] amyloidosis, anti-inflammatory therapy in serum A amyloid-osis [AA], and antisense RNA therapy in transthyretin amyloidosis [ATTR]), organ transplantation may also be a means to reduce amyloidogenic protein, e.g., in types of amyloid-osis in which the variant precursor is produced by the liver. Heart transplantation is a life-saving approach to the treatment of patients with advanced cardiac amyloidosis; however, amyloidosis may still be considered a contraindication to the procedure despite data supporting improved outcomes, similar to patients with other indications. Kidney transplantation is associated with particularly favorable outcomes in patients with amyloidosis, especially if the precursor protein has been eliminated. Overall, outcomes of solid organ transplantation are improving, but more data are needed to refine the selection criteria and the timing for organ transplantation, which should be performed in highly experienced centers involving multidisciplinary teams with close patient follow-up to detect amyloid recurrence.

Involvement of small nerve fibres and autonomic nervous system in AL amyloidosis: comprehensive characteristics and clinical implications

Peripheral nerve involvement in immunoglobulin light chain (AL) amyloidosis is common, characterised by severe progressive mixed neuropathy with autonomic dysfunction but there is limited data on the implications and the characteristics of small nerve fibres dysfunction (SNFD). The aim of our prospective study was to evaluate SNFD and its clinical implications in newly diagnosed AL patients. Twenty-three consecutive patients (10 male, mean age 61.78 years) and 21 age- and gender-matched healthy controls (8 male, mean age 61.28 years) underwent clinical evaluation and standard nerve conduction studies (NCS), baroreflex sensitivity (BRS) test, quantitative sensory testing (QST) and skin biopsy at the lower leg for measuring the density of the nerve fibres innervating the epidermis (IENFD). Axonal degeneration of the large nerve fibres was revealed in 15 out of 23 patients while SNFD was indicated by QST and skin biopsy in 56% and 61% of the patients respectively. BRS index significantly correlated with the IENFD and the QST results while low IENFD was associated with significantly poorer survival. Our study provides new insights and also an initial evaluation of new tools for assessment of the involvement of autonomic and small nerve fibres in AL amyloidosis. These findings also appear to have prognostic implications.

Cardiac Care of Patients with Cardiac Amyloidosis

Cardiac amyloidosis, the majority of cases of which are due to immunoglobulin light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR), affects different aspects of the heart and cardiovascular system. Amyloid-induced cardiomyopathy, clinically manifesting with heart failure and electrophysiological abnormalities, has distinct characteristics compared to non-amyloid cardiomyopathies. Accordingly, specific management strategies are required. This paper will review the cardiovascular manifestations of patients with cardiac amyloidosis and their suggested treatment strategies, emphasizing the importance of multidisciplinary care.

Comparison of different techniques to identify cardiac involvement in immunoglobulin light chain (AL) amyloidosis

We retrospectively reviewed the utility of N-terminal prohormone of brain natriuretic peptide (NT-proBNP) and transthoracic echocardiogram (TTE) in diagnosing cardiac involvement in patients with biopsy-proven systemic immunoglobulin light chain amyloidosis seen at the Mayo Clinic between 1 January 2006 and 30 December 2015. We analyzed 2 cohorts: patients undergoing endomyocardial biopsy for suspicion of cardiac involvement (cohort 1) and patients who had serum NT-proBNP and comprehensive echocardiographic evaluation at diagnosis (cohort 2). Of 179 patients undergoing endomyocardial biopsy (cohort 1), 173 (97%) had evidence of amyloid deposition, with 159 having NT-proBNP performed at the time of the procedure. The NT-proBNP was elevated (>300 pg/mL) in all 159 patients (sensitivity, 100%; median NT-proBNP, 4917 pg/mL; range, 355-69 541). The left ventricular ejection fraction, interventricular septal thickness, and strain rate were abnormal in 89/168 (53%), 102/64 (61%) and 92/95 (97%), respectively. Among cohort 2 (n = 342), 259 (76%) had an elevated NT-proBNP, of whom 237 (92%) had an abnormality detected on TTE. Of 83 patients with normal NT-proBNP <300 pg/mL, 27 (33%) had an abnormality on TTE (all with borderline strain rate -18% to -15%). Only 5/27 patients were considered to have possible early cardiac involvement and none had any other diagnostic or classical features of amyloidosis on TTE. The combination of NT-proBNP and comprehensive echocardiographic evaluation can diagnose cardiac amyloidosis negating the need for endomyocardial biopsy. A negative NT-proBNP rules out clinically meaningful cardiac involvement and may obviate the routine use of TTE in patients with a low clinical suspicion of cardiac amyloidosis.

The Pathology of Amyloidosis in Classification: A Review

BACKGROUND

The amyloidoses are a rare and heterogeneous group of disorders that are characterized by the deposition of abnormally folded proteins in tissues ultimately leading to organ damage. The deposits are mainly extracellular and are recognizable by their affinity for Congo red and their yellow-green birefringence under polarized light. Current classification of amyloid in medical practice is based on the amyloid protein type. To date, 36 proteins have been identified as being amyloidogenic in humans.

SUMMARY

in clinical practice, it is critical to distinguish between treatable versus non-treatable amyloidoses. Moreover, amyloidoses with a genetic component must be distinguished from the sporadic types and systemic amyloidoses must be distinguished from the localized forms. Among the systemic amyloidoses, AL continues to be the most common amyloid diagnosis in the developed world; other clinically significant types include AA, ALECT2, and ATTR. The latter is emerging as an underdiagnosed type in both the hereditary and wild-type setting. Other hereditary amyloidoses include AFib, several amyloidoses derived from apolipoproteins, AGel, ALys, etc. In a dialysis setting, systemic amyloid derived from β2 microglobulin (Aβ2M) should be considered, although a very rare hereditary variant has also been reported; several amyloidoses may be typically associated with aging and several iatrogenic types have also emerged. Determination of the amyloid protein type is imperative before specific therapy can be implemented and the current methods are briefly summarized. A brief overview of the target organ involvement by amyloid type is also included. Key Messages: (1) Early diagnosis of amyloidosis continues to pose a significant challenge and requires the participation of many clinical and laboratory specialties. (2) Determination of the protein type is imperative before specific therapy can be implemented. (3) While mass spectrometry has emerged as the preferred method of amyloid typing, careful application of immune methods is still clinically useful but caution and experience, as well as awareness of the limitations of each method, are necessary in their interpretation. (4) While the spectrum of amyloidoses continues to expand, it is critical to distinguish between those that are currently treatable versus those that are untreatable and avoid causing harm by inappropriate treatment.

Conventional Therapy for Amyloid Light-Chain Amyloidosis

The vast majority of patients with light-chain (AL) amyloidosis are not eligible for stem cell transplant and are treated with conventional chemotherapy. Conventional regimens are based on various combinations of dexamethasone, alkylating agents, proteasome inhibitors, and immunomodulatory drugs. The choice of these regimens requires a careful risk stratification, based on the extent of amyloid organ involvement, comorbidities, and the characteristics of the amyloidogenic plasma cell clone. Most patients are treated upfront with bortezomib and dexamethasone combined with cyclophosphamide or melphalan. Cyclophosphamide does not compromise stem cell mobilization and harvest and is more manageable in renal failure. Melphalan can overcome the effect of t(11;14), which is associated with lower response rates and shorter survival in subjects treated with bortezomib and dexamethasone, or in combination with cyclophosphamide. Lenalidomide and pomalidomide are the mainstay of rescue treatment. They are effective in patients exposed to bortezomib, dexamethasone, and alkylators, but deep hematologic responses are rare. Ixazomib, alone or in combination with lenalidomide, increases the rate of complete responses in relapsed/refractory patients. Conventional chemotherapy regimens will represent the backbone for future combinations, particularly with anti-plasma-cell immunotherapy, that will further improve response rates and outcomes.

A validated composite organ and hematologic response model for early assessment of treatment outcomes in light chain amyloidosis

Newly diagnosed AL amyloidosis patients were evaluated to develop a model for early assessment of treatment benefit at 6 months, integrating both hematologic (HR) and organ response (OR) assessment (testing cohort, Mayo: n = 473; validation cohort, Pavia: n = 575). Multiple OR were assessed as follows: All OR (AOR): response in all organs, mixed OR (MOR): response in some organs, no OR (NOR)]. AOR rates at 6 months improved with deepening HR; complete response (CR; 38%, 35%), very good partial response (VGPR; 30%, 26%), and partial response (PR; 16%, 21%), respectively. A composite HR/OR (CHOR) model was developed using incremental scoring based on hazard ratios with scores of 0–3 for HR (0—CR, 1—VGPR, 2—PR, 3—no response) and 0–2 for OR (0—AOR, 1—MOR, 2—NOR). Patients could be divided into two distinct CHOR groups (scores 0–3 and 4–5), with median OS in group 1 and group 2: Not reached vs. 34 months, p < 0.001 [Mayo] and 87 vs. 23 months, p < 0.001 [Pavia]. In conclusion, we developed a model that can assess multiple organs concurrently, and integrate both HR and OR assessments to determine early clinical benefit with treatment, which may be used as a surrogate end-point in trials and to compare outcomes with different therapies.

High-Dose Melphalan and Autologous Peripheral Blood Stem Cell Transplantation in AL Amyloidosis

AL amyloidosis is a systemic amyloidosis and is associated with an underlying plasma cell dyscrasia. High-dose intravenous melphalan and autologous stem cell transplantation was developed for the treatment of AL amyloidosis in the early 1990s and was prompted by its success in myeloma. This application has evolved significantly over the past three decades. This review provides a comprehensive assessment of eligibility criteria, stem cell collection, and mobilization strategies and regimens, risk-adapted melphalan dosing, role for induction and consolidation therapies as well as long-term outcome with respect to survival, hematologic response and relapse as well as organ responses following stem cell transplantation. Continued efforts to refine patient selection and management, and incorporate novel anti-plasma cell agents in combination or sequentially to further improve outcomes in AL amyloidosis are also discussed.

Supportive Care in AL Amyloidosis

Immunoglobulin light-chain (AL) amyloidosis is a systemic disease characterized by the production and deposition of light chain-derived amyloid fibrils in different organs. Prompt treatment directed to the underlying plasma cell clone is crucial in order to achieve a rapid, deep and durable hematologic response. The decrease in the production of the amyloidogenic light chains is a required condition to obtain the organ response, which is commonly delayed. Meanwhile, supportive treatment is aimed to maintain quality of life of these patients and preserve their involved organs' function. From simple measures, such as salt restriction or compressive stockings, to very complex interventions, such as heart transplantation in very selected patients with isolated severe cardiac involvement, this supportive care is essential and has to be necessarily included in the multidisciplinary management of this disease.

Amyloidosis-the Diagnosis and Treatment of an Underdiagnosed Disease

BACKGROUND

Systemic amyloidosis is a multi-system disease caused by fibrillary protein deposition with ensuing dysfunction of the affected organ systems. Its diagnosis is often delayed because the manifestations of the disease are variable and non-specific. Its main forms are light chain (AL) amyloidosis and transthyretinrelated ATTR amyloidosis, which, in turn, has both a sporadic subtype (wildtype, ATTRwt) and a hereditary subtype (mutated, ATTRv).

METHODS

This review is based on pertinent publications that were retrieved by a selective search in PubMed covering the years 2005 to 2019.

RESULTS

No robust epidemiological figures are available for Germany to date. Both AL amyloidosis and hereditary ATTR amyloidosis are rare diseases, but the prev - alence of ATTRwt amyloidosis is markedly underestimated. The diagnostic algorithm is complex and generally requires histological confirmation of the diagnosis. Only cardiac ATTR amyloidosis can be diagnosed non-invasively with bone scintigraphy once a monoclonal gammopathy has been excluded. AL amyloidosis can be considered a complication of a plasma cell dyscrasia and treated with reference to patterns applied in multiple myeloma. Despite the availability of causally directed treatment, it has not yet been possible to reduce the mortality of advanced cardiac AL amyloidosis. Three drugs (tafamidis, patisiran, and inotersen) are now available to treat grade 1 or 2 polyneuropathy in ATTRv amyloidosis, and further agents are now being tested in clinical trials. It is expected that tafamidis will soon be approved in Germany for the treatment of cardiac ATTR amyloidosis.

CONCLUSION

The diagnosis of amyloidosis is difficult because of its highly varied presentation. In case of clinical suspicion, a rapid, targeted diagnostic evaluation and subsequent initiation of treatment should be performed in a specialized center. When the new drugs to treat amyloidosis become commercially available, their use and effects should be documented in nationwide registries.

Immunoelectron microscopy and mass spectrometry for classification of amyloid deposits

Amyloidosis is a shared name for several rare, complex and serious diseases caused by extra-cellular deposits of different misfolded proteins. Accurate characterization of the amyloid protein is essential for patient care. Immunoelectron microscopy (IEM) and laser microdissection followed by tandem mass spectrometry (LMD-MS) are new gold standards for molecular subtyping. Both methods perform superiorly to immunohistochemistry, but their complementarities, strengths and weaknesses across amyloid subtypes and organ biopsy origin remain undefined. Therefore, we performed a retrospective study of 106 Congo Red positive biopsies from different involved organs; heart, kidney, lung, gut mucosa, skin and bone marrow. IEM, performed with gold-labelled antibodies against kappa light chains, lambda light chains, transthyretin and amyloid A, identified specific staining of amyloid fibrils in 91.6%; in six biopsies amyloid fibrils were not identified, and in two, the fibril subtype could not be established. LMD-MS identified amyloid protein signature in 98.1%, but in nine the amyloid protein could not be clearly identified. MS identified protein subtype in 89.6%. Corresponding specificities ranged at organ level from 94-100%. Concordance was 89.6-100% for different amyloid subtypes. Importantly, combined use of both methods increased the diagnostic classification to 100%. Some variety in performances at organ level was observed.

Survival impact of achieving minimal residual negativity by multi-parametric flow cytometry in AL amyloidosis

Response assessment in light chain (AL) amyloidosis is challenging given the low level of circulating free light chains usually seen. Multi-parametric flow cytometry (MFC) from a marrow aspirate was demonstrated to retain a prognostic significance in several recent studies. In this work, 82 AL patients who had MFC study at end of therapy were analysed based on whether clonal plasma cells were detected or not. Among patients who achieved deep response (i.e. very good partial response or complete response) to first-line therapy, lack of clonal marrow plasma cells as measured by MFC was associated with improved progression-free survival (PFS) compared to patients with residual clonal plasma cells (3-year PFS 88% vs. 46%, p = .003), particularly among patients who achieved a complete response (3-year PFS 100% vs. 33%, p = .001). Absence of clonal plasma cells by MFC compared with patients with detectable clonal plasma cells among deep responders was associated with lower level of involved light chain (involved free light chain (iFLC), median 1.1 vs. 1.7 mg/dL; p = .02) and higher frequency of renal response (100% vs. 68%; p = .005). Further studies are needed to determine if MFC should be incorporated into response criteria in AL amyloidosis.

[The prognostic value of baseline serum free light chain in immunoglobulin light-chain cardiac amyloidosis]

Objective: To analyze the prognostic value of baseline serum free light chain (sFLC) in immunoglobulin light-chain cardiac amyloidosis (AL-CA) . Methods: Thirty patients diagnosed with AL-CA from January 2012 to December 2016 at Beijing Chaoyang Hospital were included in this study to retrospectively evaluate the clinical data. The cut-off value of dFLC (involved sFLC minus uninvolved sFLC) was determined according to the receiver operator characteristic curve (ROC) and grouped, the prognoses of both groups were evaluated. Results: The onset age of all AL-CA patients was 57 years old. It occurred more commonly in men (21 cases, 70%) and the light chains of immunoglobulin composed mainly of type λ (22 cases, 73.3%) . Renal involvements occurred in 17 cases (56.7%) . The median value of difference between involved and uninvolved serum immunoglobulin free light chain levels (dFLC) was 162.9 (57.9-401.6) mg/L. More subjects in the high dFLC group had higher BNP (P=0.005) , and shorter median survival than those in the low dFLC group (15 months vs 47 months, P<0.001) . Similar results of median survival were observed when the patients were redivided by a new cut-off value of 180 mg/L for dFLC (high dFLC group: 22 months, low dFLC group: 40 months, P=0.001) , or a κ/λ ratio in which patients with κ type sFLC-ratio<3.79 and λ type sFLC-ratio≥0.06 were grouped into the low sFLC-ratio (37 months) , and the reverse the high sFLC-ratio ones (25 months, P=0.021) . In multivariate analysis, dFLC and New York Heart Association (NYHA) classification of cardiac function were two risk factors associated with all-cause mortality in patients, of them the hazard ratio for higher dFLC was 12.13 (95%CI 2.98-49.30, P<0.001) . Conclusion: Measurement of the sFLC level could implicate the prognosis of AL-CA.

Nonlymphoplasmacytic lymphomas associated with light-chain amyloidosis

The authors report on the subset of AL amyloidosis patients with nonlymphoplasmacytic lymphoma, emphasizing a predominance of marginal zone lymphoma, frequent delay in diagnosis, and a generally poor prognosis.

Long-term outcomes of IMiD-based trials in patients with immunoglobulin light-chain amyloidosis: a pooled analysis

Rarity of light-chain amyloidosis (AL) makes randomized studies challenging. We pooled three phase II studies of immunomodulatory drugs (IMiDs) to update survival, toxicity, and assess new response/progression criteria. Studies included were lenalidomide-dexamethasone (Len-Dex) (n = 37; years: 2004–2006), cyclophosphamide-Len-Dex (n = 35; years: 2007–2008), and pomalidomide-Dex (n = 29; years: 2008–2010) trial. Primary endpoint was hematologic response. Overall survival (OS) was calculated from registration to death and progression-free survival (PFS) was calculated from registration to progression or death. Hematologic, cardiac, and renal response/progression was assessed using the modern criteria. Analysis included 101 patients, with a median age of 65 years, 61% male, 37 newly diagnosed (ND), and 64 relapsed/refractory (RR). Median follow-up was 101 months (range 17–150) and 78% of patients died. OS and PFS for pooled cohort were 31 and 15 months, respectively. Forty-eight patients achieved a hematologic response; for ND, 10 patients (28%) achieved ≥VGPR (very good partial response) and 8 (14%) among the RR. Only cardiac stage was prognostic for OS. Common grade ≥3 toxicities were hematologic, fatigue, and rash, and were similar among studies. Hematologic and renal responses occurred more frequently and rapidly using modern response criteria; cardiac response was less frequent but occurred quickly. IMiDs can result in long progression-free intervals/survival with tolerable toxicities. The new response/progression criteria were rapid and allows for tailoring therapy.

Temporal artery involvement in AL amyloidosis: an important differential diagnosis for giant cell arteritis. A case report and literature review

AL amyloidosis (AL) is a systemic disorder due to extracellular tissue deposition of amyloid fibrils, composed of immunoglobulin light chains. Since the description of AL involving temporal arteries in 1986, this disorder has been known as one of the differential diagnoses of giant cell arteritis (GCA). We encountered a case of an elderly female presenting with headache and tender and enlarged temporal arteries, that was pathologically diagnosed with temporal artery involvement of AL due to Bence-Jones-type MM. To our knowledge, this was the first case of AL with temporal artery involvement in Japan, that presented with GCA-like features. Literature review of AL cases with temporal artery involvement showed close similarity between these disorders, but suggested that vasculature involvement (extremity claudication, kidney or heart), macroglossia, carpal tunnel syndrome and normal or low (<0.5 mg/dL) CRP levels may predict AL rather than GCA. Physicians should keep in mind that AL involving temporal arteries can be a pitfall in the diagnosis of GCA, as seen in our and previous cases.

Inherent Biophysical Properties Modulate the Toxicity of Soluble Amyloidogenic Light Chains

In light chain amyloidosis (AL), fibrillar deposition of monoclonal immunoglobulin light chains (LCs) in vital organs, such as heart, is associated with their severe dysfunction. In addition to the cellular damage caused by fibril deposition, direct toxicity of soluble prefibrillar amyloidogenic proteins has been reported, in particular, for cardiotoxicity. However, the molecular bases of proteotoxicity by soluble LCs have not been clarified. Here, to address this issue, we rationally engineered the amino acid sequence of the highly cardiotoxic LC H6 by introducing three residue mutations, designed to reduce the dynamics of its native state. The resulting mutant (mH6) is less toxic than its parent H6 to human cardiac fibroblasts and C. elegans. The high sequence and structural similarity, together with the different toxicity, make H6 and its non-toxic designed variant mH6 a test case to shed light on the molecular properties underlying soluble toxicity. Our comparative structural and biochemical study of H6 and mH6 shows closely matching crystal structures, whereas spectroscopic data and limited proteolysis indicate that H6 displays poorly cooperative fold, higher flexibility, and kinetic instability, and a higher dynamic state in its native fold. Taken together, the results of this study show a strong correlation between the overall conformational properties of the native fold and the proteotoxicity of cardiotropic LCs.

Amyloidosis and Ocular Involvement: an Overview

Purpose: To describe the ophthalmic manifestations of amyloidosis and the corresponding therapeutic measures.Methods: The 178 patients included in the study had different types of amyloidosis, diagnosed at a single internal medicine institution (Bari, Italy). To provide a comprehensive review of the types of amyloidosis that can be associated with ocular involvement, the images and clinical descriptions of patients with amyloidosis structurally related to gelsolin, keratoepithelin and lactoferrin were obtained in collaborations with the ophthalmology departments of hospitals in Mainz (Germany) and Helsinki (Finland).Results: Overall, ocular morbidity was detected in 41 of the 178 patients with amyloidosis (23%). AL amyloidosis was diagnosed in 18 patients with systemic disease, 3 with multiple myeloma, and 11 with localized amyloidosis. AA amyloidosis was detected in 2 patients with rheumatoid arthritis and 3 with Behçet syndrome, and transthyretin amyloidosis in 4 patients. The treatment of AL amyloidosis is based on chemotherapy to suppress the production of amyloidogenic L-chains and on surgical excision of orbital or conjunctival masses. AA amyloidosis is managed by targeting the underlying condition. Vitreous opacities and additional findings of ocular involvement in patients with transthyretin amyloidosis indicate the need for pars plana vitrectomy. Gelsolin amyloidosis, characterized by lattice corneal amyloidosis and polyneuropathy, results in recurrent keratitis and corneal scarring, such that keratoplasty is inevitable. In patients with lattice corneal dystrophies associated with amyloid deposits of keratoepithelin fragments, corneal transparency is compromised by deposits of congophilic material in the subepithelial layer and deep corneal stroma. Patients with established corneal opacities are treated by corneal transplantation, but the prognosis is poor because recurrent corneal deposits are possible after surgery. In patients with gelatinous drop-like dystrophy, the amyloid fibrils that accumulate beneath the corneal epithelium consist of lactoferrin and can severely impair visual acuity. Keratoplasty and its variants are performed for visual rehabilitation.Conclusion: A routine ophthalmic follow-up is recommended for all patients with established or suspected amyloidosis, independent of the biochemical type of the amyloid. Close collaboration between the ophthalmologist and the internist will facilitate a more precise diagnosis of ocular involvement in amyloidosis and allow the multidisciplinary management of these patients.Abbreviations: CD: corneal dystrophy; CLA: corneal lattice amyloidosis; CNS: central nervous system; CT: computed tomography; FAP: familial amyloidotic polyneuropathy; GDLCD: gelatinous drop-like corneal dystrophy; GLN: gelsolin; LCD: lattice corneal dystrophy; MRI: magnetic resonance imaging; OLT: orthotopic liver transplantation; TEM: transmission electron microscopy; TGFBI: transforming growth factor β induced; TTR: transthyretin.

Sjögren syndrome-related plasma cell disorder and multifocal nodular AL amyloidosis: clinical picture and pathological findings

Background: Localized nodular deposits of AL amyloid are seen in different tissues/organs; however, the pathogenesis of this form of amyloidosis remains unclear. Recently, Sjögren syndrome combined with localized nodular AL amyloidosis has been noted. Here, we report Sjögren syndrome cases showing multifocal nodular AL amyloidosis and the followed benign course. Materials and methods: We investigated the clinical pictures and histopathological findings of three cases with both presence of Sjögren syndrome and localized nodular AL amyloidosis, paying a special attention to the distribution of amyloidoma. Results: All three cases were middle-aged females. In two of three cases localized deposits of AL amyloid preceded Sjögren syndrome. Amyloidoma was detected in scalp, eyelid, cheek, larynx, trachea, lung and breast, and around these amyloid-deposited lesions infiltration of plasma cells was seen. Pulmonary amyloidosis was consistently accompanied with parenchymal cystic lesions, but this amyloidosis did not produce any significant respiratory symptoms. Some of large pulmonary amyloidomas showed cavity formation and subsequent shrinkage. In two cases amyloid deposition was found on gastric mucosa. Two cases received small doses of oral prednisone, with no further appearance of amyloidoma. Conclusion: Sjögren syndrome-related plasma cell disorder may be responsible for the formation of this unique multifocal nodular AL amyloidosis.

A new era of amyloidosis: the trends at a major US referral centre

Objective: To characterize the changing spectrum of amyloidosis classes, as well as patient demographics, at a major US referral centre. Patients and methods: A retrospective analysis was conducted of all referrals to the Amyloidosis Centre at Boston University and Boston Medical Centre over the last 3 decades. Results: A total of 3987 new patients with amyloidosis were evaluated between 1990 and 2018 with the average number of new cases per year increasing 2.5-fold during this period. Systemic immunoglobulin light-chain (AL) amyloidosis decreased in proportion with each decade from 77% to 69% to 50% of new cases. Meanwhile, ATTR amyloidosis increased from 12% to 16% to 29%, predominately due to more diagnosis of ATTRwt and ATTRV122I amyloidosis. Gender and race profile differences, while changing over the observed time period, persisted among amyloidosis patients. Conclusion: Amyloid diseases are more widely recognized and classes of amyloidosis, including ATTRwt and ATTRV122I, once considered rare are now increasingly diagnosed. These data likely reflect a national trend of increased amyloidosis awareness facilitated by accessible diagnostic approaches, emerging treatments, and coordinated educational initiatives. ClinicalTrials.gov identifier: NCT00898235.

Increasing Rate of Hospital Admissions in Patients With Amyloidosis (from the National Inpatient Sample)

Cardiac amyloidosis is an increasingly recognized cause of heart failure with preserved or mildly reduced ejection fraction with emerging treatment options. We sought to analyze the temporal trends and impact of hospital admissions in patients with amyloidosis. The National Inpatient Sample was queried to identify patients from 2005 to 2014 who were hospitalized with a diagnosis of amyloidosis using ICD9 codes. Trends over time of prevalence, demographics, co-morbidities, and outcomes were described. Propensity-matching was used to assess the impact of amyloidosis on in-hospital outcomes, including mortality. A total of 156,914 admissions in patients with amyloidosis (age 69.86 +/- 12.33 years, 45.7% female, 68.5% Caucasian) were identified. Hospitalizations more than doubled with a peak of 21,740 per year and 62 per 100,000 admissions in 2014. Over time, patients admitted with amyloidosis were older and more likely to have co-morbid medical conditions. A diagnosis of heart failure was present in 34.7% of patients, increased over time (p = 0.001), and was associated with further morbidity and mortality. In a propensity-matched analysis, patients admitted with amyloidosis had a longer length of stay (7.5 vs 6.2 days), were less likely to be discharged home (43.6% vs 48.7%), and were more likely to die during the hospitalization (7.4% vs 4.9%, p <0.001 for all). In conclusion, inpatient hospitalizations in the United States in patients with amyloidosis have increased over time and are associated with high morbidity and mortality, particularly when there is concomitant heart failure.

Bone marrow plasma cells 20% or greater discriminate presentation, response, and survival in AL amyloidosis

We explored the association between bone marrow plasma cells (BMPCs) and disease presentation and outcome among 1574 AL patients. Three BMPC groups were formulated: <5% (n = 231, 15% of study population), 5-19% (n = 1045, 66%), and ≥20% (n = 298, 19%). Heart and renal involvement were more and less prevalent, respectively, with increasing BMPCs. Patients with ≥20% BMPCs had higher likelihood for classic myeloma phenotype with less skewed lambda restriction, a higher rate of intact immunoglobulin secretion, a lower hemoglobin and higher rates of hypercalcemia and bone lytic lesions. High-risk cytogenetic abnormalities were more common in ≥20% BMPCs. Complete hematological response was less frequent with rising BMPCs. The median survival was inversely associated with the BMPC groups (81, 33, 12 months for <5%, 5-19%, and ≥20% BMPCs, respectively; P < 0.001). Survival discrimination was maintained at 1-year landmark and in those who achieved a complete response. Multivariate analysis accounting for known prognostic markers yielded an independent prognostic role for ≥20% BMPCs, but not for the other BMPC groups. AL patients with 20% or greater BMPCs have poorer outcome independent of their cardiac risk category and stem cell transplant eligibility. Distinct interventions in these patients should be explored to improve outcome.

The efficacy and safety of bortezomib-based chemotherapy for immunoglobulin light chain amyloidosis: A systematic review and meta-analysis

BACKGROUND

The role of bortezomib in the treatment of immunoglobulin light chain (AL) amyloidosis is not well defined. We performed this meta-analysis to evaluate the efficacy and safety of bortezomib-based regimens in patients with AL amyloidosis who are not eligible for or refuse autologous stem cell transplantation.

METHODS

A systematic search of Medline, Embase, and the Cochrane Library was conducted to identify related studies.

RESULTS

Twenty-four studies with 1238 patients were included. The pooled overall response rate (ORR) and complete hematological response rate (CHR) were 0.72 (95% CI, 0.67-0.77) and 0.35 (95% CI, 0.30-0.40), respectively. Bortezomib significantly improved the outcome of ORR compared to other regimens (RR 1.28, 95% CI, 1.04-1.57, P = .02). Similar results were observed in CHR (RR 1.90, 95% CI, 1.45-2.50, P < .001) and cardiac response (RR 2.03, 95% CI, 1.31-3.13, P = .002), but not in overall survival (HR 0.82, 95% CI, 0.62-1.09, P = .17). In addition, once-weekly bortezomib was associated with improved overall survival compared with twice-weekly bortezomib (HR 0.52, 95% CI, 0.27-0.99, P = .05). Peripheral neuropathy was the most widely reported adverse event. Incorporation of bortezomib into the standard melphalan + dexamethasone setting showed a trend of increased serious adverse events, though this was not statistically significant (RR 1.29, 95% CI, 0.95-1.75, P = .10).

CONCLUSIONS

Current evidence indicates that bortezomib-based regimens might be effective and safe therapies for patients with AL amyloidosis. There is a great need to conduct more well-designed randomized controlled trials to provide high-quality evidence.